Portable electronic devices, such as cellular phones, two-way pagers, laptop computers, personal digital assistants (PDAs), and music players, are popular and have many uses with consumers and businesses alike. Most portable electronic devices are designed to be small, compact, battery powered, and yet still provide a host of features and conveniences. The typical portable electronic device contains components, such as integrated circuits, discrete semiconductor devices, passive devices, piezoelectric devices, liquid crystal display (LCD), and mechanical devices, encased within a plastic or metal housing.
Many of the components in the portable electronic device require a direct current (DC) operating potential to function. Some components are continuously connected to the DC power supply voltage. Other components, such as the LCD and piezoelectric devices, receive the DC power supply voltage only when activated. For such components, a load switching circuit is used to connect the DC power supply to the load component to activate the device. The load switching circuit receives an enable signal which couples the DC operating potential through the load switch to the load component to allow it to function.
The load switching circuit is typically implemented with discrete transistors and discrete passive devices. The default state of the load switching circuit is to disconnect the DC power supply from the load component. A discrete pass transistor is rendered conductive in response to the enable signal to couple the DC operating potential to the load component.
Component size and level of integration are important factors in the design of the portable electronic devices. The space available on the printed circuit boards of portable electronic devices is usually a premium design consideration. The designers and manufacturers of portable electronic devices continuously demand faster speed, more functionality, less power consumption, smaller size, and higher integration when selecting electronic component parts for their systems. The discrete components used to implement the load switching circuit consumes more area of the printed circuit board than many portable electronic device manufacturers may prefer.
A need exists for semiconductor devices and packages which consume less area in portable electronic devices having limited board space.